I didn't realize they played 4 quarters during the Jamboree. What I saw was Joplin couldn't run the ball, but was successful throwing up jump balls. For which the Joplin receivers made great plays. On the flip side Lamar was not very effective running the ball. Lamar did get to 1 or 2 yard line then brought in the JV, I can't explain that one. But yes class 6 Joplin did kick Lamar's class 2 butt in 12 plays....congratulations Joplin 2018 Jamboree champions.
Maybe Lamar put in their JV because they possibly scripted it that way to put them in after a set amount of plays. May have been more concerned with developing the future and preparing kids for the season than anything else.